Avoid losing focus when block decorations go offscreen (#14815)

Release Notes:

- Fixed a bug that caused focus to be lost when renames and inline
assists were scrolled offscreen.

---------

Co-authored-by: Nathan <nathan@zed.dev>

crates/diagnostics/src/diagnostics.rs

@@ -10,7 +10,7 @@ use anyhow::Result;
 use collections::{BTreeSet, HashSet};
 use editor::{
     diagnostic_block_renderer,
-    display_map::{BlockDisposition, BlockId, BlockProperties, BlockStyle, RenderBlock},
+    display_map::{BlockDisposition, BlockProperties, BlockStyle, CustomBlockId, RenderBlock},
     highlight_diagnostic_message,
     scroll::Autoscroll,
     Editor, EditorEvent, ExcerptId, ExcerptRange, MultiBuffer, ToOffset,
@@ -85,7 +85,7 @@ struct DiagnosticGroupState {
     primary_diagnostic: DiagnosticEntry<language::Anchor>,
     primary_excerpt_ix: usize,
     excerpts: Vec<ExcerptId>,
-    blocks: HashSet<BlockId>,
+    blocks: HashSet<CustomBlockId>,
     block_count: usize,
 }